A lithium-ion secondary battery (hereinafter sometimes referred to as “lithium secondary battery”) has characteristics that it has a higher energy density and is operable at a high voltage compared to other secondary batteries. Therefore, it is used for information devices such as a cellular phone, as a secondary battery which can be easily reduced in size and weight, and nowadays there is also an increasing demand for the lithium-ion secondary battery to be used as a power source for large-scale apparatuses such as electric vehicles and hybrid vehicles.
A lithium-ion secondary battery comprises a cathode layer, an anode layer, and an electrolyte layer disposed between them. An electrolyte to be employed in the electrolyte layer is, for example, a non-aqueous liquid or a solid. When the liquid is used as the electrolyte (hereinafter, the liquid being referred to as “electrolytic solution”), it permeates into the cathode layer and the anode layer easily. Therefore, an interface can be formed easily between the electrolytic solution and active materials contained in the cathode layer and the anode layer respectively, and the battery performance can be easily improved. However, since commonly used electrolytic solutions are flammable, it is necessary to mount a system to ensure safety. On the other hand, if a nonflammable solid electrolyte (hereinafter referred to as “solid electrolyte”) is used, the above system can be simplified. As such, lithium-ion secondary batteries having a layer containing a solid electrolyte have been suggested. (hereinafter, the layer being referred to as “solid electrolyte layer” and the battery being referred to as “solid battery”).
As a technique related to such a solid battery, Patent Document 1 for example discloses a method for manufacturing a lithium-ion second battery, the method includes the steps of: preparing a cathode active material in powder form; preparing an anode active material in powder form; preparing an electrolyte material in powder form which includes lithium element; filling up the cathode active material, the anode active material, and the electrolyte material into a predetermined mold in a way that the electrolyte material exists being mixed with the cathode material in an upper portion or a lower portion of the predetermined mold, at the same time in a way that only the electrolyte material exists in a central portion of the predetermined mold; and pressing the cathode active material, the anode active material and the electrolyte material to form a solid cathode layer composed of a mixture of the cathode active material and the electrolyte material, a solid anode layer, and a solid electrolyte layer including lithium.